Sintered electrodes for capacitor anodes, cathodes, anode systems, and cathode systems

ABSTRACT

A capacitor case sealed to retain electrolyte; a sintered anode disposed in the capacitor case, the sintered anode having a shape wherein the sintered anode includes a mating portion; a conductor coupled to the sintered anode, the conductor sealingly extending through the capacitor case to a terminal disposed on an exterior of the capacitor case; a sintered cathode disposed in the capacitor case, the sintered cathode having a shape that mates with the mating portion of the sintered anode such that the sintered cathode matingly fits in the mating portion of the sintered anode; a separator between the sintered anode and the sintered cathode; and a second terminal disposed on the exterior of the capacitor case and in electrical communication with the sintered cathode, with the terminal and the second terminal electrically isolated from one another.

CLAIM OF PRIORITY

This application is a continuation of U.S. application Ser. No.15/267,534, filed Sep. 16, 2016, which claims the benefit of priorityunder 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No.62/219,273, filed on Sep. 16, 2015, which is herein incorporated byreference in its entirety.

TECHNICAL FIELD

This document relates generally to energy storage and particularly tosintered electrodes to store energy in an implantable medical device.

BACKGROUND

Electrical stimulation therapy has been found to benefit some patients.For example, some patients suffer from an irregular heartbeat orarrhythmia and may benefit from application of electrical stimulation tothe heart. Some patients suffer from a particular type of arrhythmiacalled a fibrillation. Fibrillations may affect different regions of theheart, such as the atria or the ventricles. When a fibrillation occursin the ventricles, the heart's ability to pump blood is dramaticallyreduced, putting the patient at risk of harm. It has been found thatapplying an electrical stimulation to the patient can effectively treatpatients suffering disorders such as from fibrillation by restoring aregular heartbeat.

Because disorders such as fibrillations can happen at any time, it ishelpful to have a device that is easily accessible to treat them. Insome cases, it is helpful if that device is portable or implantable. Indeveloping a device that is portable or implantable, it is helpful tohave access to components that are compact and lightweight and that canperform to desired specifications.

SUMMARY

In example 1, an apparatus including a capacitor case sealed to retainelectrolyte; a sintered anode disposed in the capacitor case, thesintered anode having a shape wherein the sintered anode includes amating portion; a conductor coupled to the sintered anode, the conductorsealingly extending through the capacitor case to a terminal disposed onan exterior of the capacitor case; a sintered cathode disposed in thecapacitor case, the sintered cathode having a shape that mates with themating portion of the sintered anode such that the sintered cathodematingly fits in the mating portion of the sintered anode; a separatorbetween the sintered anode and the sintered cathode; and a secondterminal disposed on the exterior of the capacitor case and inelectrical communication with the sintered cathode, with the terminaland the second terminal electrically isolated from one another.

In example 2, the subject matter of example 1 can optionally include thesintered anode having a non-rectangular shape.

In example 3, the subject matter of example 1 or 2 can optionallyinclude the sintered cathode having a non-rectangular shape.

In example 4, the subject matter of any of examples 1-3 can optionallyinclude the mating portion of the sintered anode being a void spaceshaped like a fin and the sintered cathode having a fin shape.

In example 5, the subject matter of any of examples 1-4 can optionallyinclude the mating portion of sintered anode being rounded cut-outs atone or more corners of the sintered anode.

In example 6, the subject matter of example 5 can optionally include thesintered cathode having a cylindrical shape

In example 7, the subject matter of example 6 can optionally include thesintered anode having a triangular shape with the rounded cut-outs atthe three corners of the triangular shape.

In example 8, the subject matter of example 7 can optionally include aplurality of sintered anodes having triangular shapes and arrangedtogether in a side by side configuration with a plurality of cylindricalcathodes located at the rounded out corners of each of the plurality ofsintered anodes.

In example 9, the subject matter of any of claims 1-8 can optionallyinclude the separator being a high dielectric polymer directly appliedto an outer surface of the sintered cathode.

In example 10, the subject matter of any of examples 1-9 can optionallyinclude the sintered cathode having a high capacitance coating on anouter surface.

In example 11, the subject matter of any of examples 1-10 can optionallyinclude the cathode having a bed of nails structure.

In example 12, the subject matter of any of examples 1-11 can optionallyinclude the mating portion being conical and the sintered cathode beingconical.

In example 13, the subject matter of any of examples 1-12 can optionallyinclude the sintered anode and the sintered cathode being standaloneslugs that include the sintered portion, with the sintered portion beingmonolithic.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Otheraspects of the invention will be apparent to persons skilled in the artupon reading and understanding the following detailed description andviewing the drawings that form a part thereof. The scope of the presentinvention is defined by the appended claims and their legal equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate generally, by way of example, variousembodiments discussed in the present document. The drawings are forillustrative purposes only and may not be to scale.

FIG. 1 shows a schematic representation of a medical system including asintered capacitor, in accordance with one embodiment.

FIG. 2 shows an implanted medical system including a sintered capacitor,in accordance with one embodiment.

FIG. 3 shows a sintered anode and sintered cathode, in accordance withone embodiment.

FIG. 4 shows a sintered anode and sintered cathode, in accordance withone embodiment.

FIG. 5 shows a sintered anode and sintered cathode, in accordance withone embodiment.

FIG. 6 shows a sintered anode and sintered cathode, in accordance withone embodiment.

FIG. 7 shows a sintered anode and sintered cathode, in accordance withone embodiment.

FIG. 8 shows a sintered anode and sintered cathode, in accordance withone embodiment.

FIG. 9 shows a sintered anode and sintered cathode, in accordance withone embodiment.

FIG. 10 shows a perspective view of sintered anode and sintered cathodesof FIG. 9, in accordance with one embodiment.

FIG. 11 shows a perspective view of sintered anode and sintered cathodesof FIG. 9, in accordance with one embodiment.

FIG. 12 shows a perspective view of a sintered anode and sinteredcathode, in accordance with one embodiment.

FIG. 13 shows a perspective view of a sintered anode and sinteredcathode, in accordance with one embodiment.

FIG. 14 shows a perspective view of a sintered anode and sinteredcathode, in accordance with one embodiment.

FIG. 15 shows a perspective view of a sintered anode and sinteredcathode, in accordance with one embodiment.

FIG. 16 shows a perspective view of a sintered anode and sinteredcathode, in accordance with one embodiment.

FIG. 17 shows a perspective view of a sintered anode and sinteredcathode, in accordance with one embodiment.

FIG. 18 shows a perspective view of a sintered anode and sinteredcathode, in accordance with one embodiment.

DETAILED DESCRIPTION

The following detailed description of the present invention refers tosubject matter in the accompanying drawings which show, by way ofillustration, specific aspects and embodiments in which the presentsubject matter may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice thepresent subject matter. References to “an”, “one”, or “various”embodiments in this disclosure are not necessarily to the sameembodiment, and such references contemplate more than one embodiment.The following detailed description is, therefore, not to be taken in alimiting sense, and the scope is defined only by the appended claims,along with the full scope of legal equivalents to which such claims areentitled.

This document concerns sintered electrodes for use in an electricalenergy storage device. Specific examples include sintered anodes formedof aluminum or its alloys. Some examples use sintered anodes formed oftantalum. Certain examples are for use in aluminum electrolyticcapacitors. Additional benefits stem from an increased surface area thatis a product of sintering.

Sintering results in many interstices (i.e., spaces) between grains ofthe electrode. Sintered electrodes resemble crushed grains withinterstices between the grains. The interstices are filled withelectrolyte, thereby increasing capacitance per unit of volume, ascapacitance is proportional to a surface area exposed to electrolyte. Anelectrode with such interstices offers improved lateral or parallelmovement of electrons in relation to a major surface of a flat electrodelayer, as etched electrodes restrict lateral movement because theetchings result in voids that are typically perpendicular to the majorsurface of the flat layer. Accordingly, some examples have a lower ESR(equivalent series resistance) compared to etched foils due to thisenhance ionic flow.

Overall, an energy storage device using the sintered electrodesdescribed here is well suited for use in an implantable medical devicesuch as a defibrillator. Because sintering can produce a variety ofshapes, sintered electrodes can be used to create energy storage devicessuch as capacitors that have custom shapes versus simple rolledcylinders or a prism having a parallelogram as its base. Further,manufacturing efficiency is improved, by easing the steps and parts inmanufacturing a capacitor and by reducing waste. The interstices arevery small, making the electrodes rigid and able to withstand handlingby a machine or assembly personnel. These electrodes demonstrate animproved energy density over etched electrodes and are therefore usefulto make smaller implantable devices that are able to deliver an amountof energy for a particular therapy.

FIG. 1 is a schematic of a medical system 100 including a sinteredcapacitor, according to some embodiments. The medical system 100represents any number of systems to provide therapeutic stimulus, suchas to a heart. Examples of medical systems include, but are not limitedto, implantable pacemakers, implantable defibrillators, implantablenerve stimulation devices and devices that provide stimulation fromoutside the body, including, but not limited to, externaldefibrillators.

Electronics 104 are to monitor the patient, such as by monitoring asensor 105, and to monitor and control activity within the system 100.In some examples, the electronics 104 are to monitor a patient, diagnosea condition to be treated such as an arrhythmia, and control delivery ofa stimulation pulse of energy to the patient. The electronics 104 can bepowered wirelessly using an inductor. Alternatively, the electronics 104can be powered by a battery 106. In some examples, electronics 104 areto direct small therapeutic bursts of energy to a patient from thebattery 106.

For therapies, such as defibrillation, that use energy discharge ratesexceeding what battery 106 is able to provide, a capacitor 108 is used.Energy from the battery 106 is controlled by the electronics 104 tocharge the capacitor 108. The capacitor 108 is controlled by theelectronics 104 to discharge to a patient to treat the patient. In someexamples, the capacitor 108 completely discharges to a patient, and inadditional examples, the capacitor is switched on to provide therapeuticenergy and switched off to truncate therapy delivery.

Some examples of a medical system 100 include an optional lead system101. In certain instances, after implantation, the lead system 101 or aportion of the lead system 101 is in electrical communication withtissue to be stimulated. For example, some configurations of lead system101 contact tissue with a stimulation electrode 102. The lead system 101couples to other portions of the system 100 via a connection in a header103. Examples of the system 101 use different numbers of stimulationelectrodes and/or sensors in accordance with the needs of the therapy tobe performed.

Additional examples function without a lead 101. Leadless examples canbe positioned in contact with the tissue to be stimulated, or can bepositioned proximal to tissue to shock the tissue to be stimulatedthrough intermediary tissue. Leadless examples can be easier to implantand can be less expensive as they do not require the additional leadcomponents. The housing 110 can be used as an electrode in leadlessconfigurations.

In certain embodiments, the electronics 104 include an electroniccardiac rhythm management circuit coupled to the battery 106 and thecapacitor 108 to discharge the capacitor 108 to provide a therapeuticpulse, such as a defibrillation pulse. In some examples, the system 100includes an anode and a cathode sized to deliver a pulse of at leastapproximately 50 joules. Other configurations can deliver larger amountsof energy. Some configurations deliver less energy, for example at least36 joules. In some examples, the energy level is predetermined toachieve a delivered energy level mandated by a governing body orstandard associated with a geographic region, such as a Europeancountry. In an additional embodiment, the anode and cathode are sized todeliver a defibrillation pulse of at least approximately 60 joules. Insome examples, this is the energy level is predetermined to achieve anenergy level mandated by a governing body of another region, such as theUnited States. In some examples, electronics 104 are to controldischarge of a defibrillation pulse so that the medical system 100delivers only the energy mandated by the region in which the system 100is used.

One characteristic of some sintered electrode examples is that at leastone anode and a cathode have a DC capacitance that is approximately 23%greater than a AC capacitance for the at least one anode and the cathodeof an etched capacitor that has 74.5 microfarads per cubic centimeter.In some examples, the at least one anode and the cathode have an ACcapacitance of at least 96.7 microfarads per cubic centimeter at 445total voltage. In some examples, this is comparable to an operatingvoltage of about 415 volts. This is a 30% improvement over an etchedcapacitor that has 74.5 microfarads per cubic centimeter. Total voltageis the voltage that allows 1 milliamp of leakage per square centimeterfor an electrode. Some examples are aged to 415 volts.

In certain examples, the capacitor 108 includes a capacitor case 113sealed to retain electrolyte. In some examples, the capacitor case 113is welded. In some instances, the capacitor case 113 is hermeticallysealed. In additional examples, the capacitor case 113 is sealed toretain electrolyte, but is sealed with a seal to allow flow of othermatter, such as gaseous diatomic hydrogen or a helium molecule. Some ofthese examples use an epoxy seal. The capacitor further includes aconductor 109 coupled to one of the electrodes of the capacitor 108. Theconductor 109 sealingly extends through the capacitor case to a firstterminal 112 disposed on an exterior of the capacitor case 113. A secondterminal 114 can be disposed on the exterior of the capacitor case 113and in electrical communication with the other electrode of thecapacitor 108. The first terminal 112 and the second terminal 114 areelectrically isolated from one another.

A hermetically sealed device housing 110 is used to house components,such as the battery 106, the electronics 104, and the capacitor 108.Hermeticity is provided by welding components into the hermeticallysealed device housing 110, in some examples. Other examples bondportions of the housing 110 together with an adhesive such as a resinbased adhesive such as epoxy. Accordingly, some examples of the housing110 include an epoxy sealed seam or port. Several materials can be usedto form housing 110, including, but not limited to, titanium, stainlesssteel, nickel, a polymeric material, or combinations of these materials.In various examples, the housing 110 and the case 113 are biocompatible.

The capacitor 108 is improved by the present electrode technology inpart because it can be made smaller and with less expense and a varietyof shapes and configurations. The improvement provided by theseelectrodes is pertinent to any application where high-energy,high-voltage, or space-efficient capacitors are desirable, including,but not limited to, capacitors used for photographic flash equipment.The present subject matter extends to energy storage devices thatbenefit from high surface area sintered electrodes including, but notlimited to, aluminum. The electrodes described here can be incorporatedinto cylindrical capacitors that are wound, in addition to stackedcapacitors.

FIG. 2 is an implanted medical system 200, implanted in a patient 201,and including a sintered capacitor, according to some embodiments. Thesystem includes a cardiac rhythm management device 202 coupled to afirst lead 204 to extend through the heart 206 to the right ventricle208 to stimulate at least the right ventricle 208. The system alsoincludes a second lead 210 to extend through the heart 206 to the leftventricle 212. In various embodiments, one or both of the first lead 204and the second lead 210 include electrodes to sense intrinsic heartsignals and to stimulate the heart. The first lead 204 is in directcontact (e.g., touching) with the right atrium 214 and the rightventricle 208 to sense and/or stimulate both those tissue regions. Thesecond lead 210 is in direct contact with the left atrium 216 and theleft ventricle 212 to sense and/or stimulate both those tissue regions.The cardiac rhythm management device 202 uses the lead electrodes todeliver energy to the heart, either between electrodes on the leads orbetween one or more lead electrodes and the cardiac rhythm managementdevice 202. Some embodiments can include epicardially or subcutaneouslyplaced leads. In some examples, the cardiac rhythm management device 202is programmable and wirelessly communicates 218 programming informationwith a programmer 220. In some examples, the programmer 220 wirelessly218 charges an energy storage device of the cardiac rhythm managementdevice 202.

The present system allows for different concepts for the design of highvoltage aluminum electrolytic capacitors. As will be discussed, thepresent system allows for reducing assembly time and cost by providingshapes that allow for ease of assembly with reduction of precise roboticassembly.

FIG. 3 shows a sintered anode 302 and a sintered cathode 304 for acapacitor, in accordance with one embodiment. The sintered anode 302includes a sintered portion 306 and one or more mating portions, such asvoid spaces 308. The sintered cathode 304 can have a shape that mateswith the void space 308 of the sintered anode 302 such that the sinteredcathode 304 matingly fits in the void space 308 of the sintered anode.In this example, both the sintered anode 302 and the sintered cathode304 have non-rectangular shapes. By using sintered cathodes 304, thesintered cathodes 304 can be smaller than previous and can be shaped andconfigured to interlock with the various sintered anode shapes.Moreover, using sintering for the anodes and cathodes helps reduce thecost and scrap of anode and cathode materials, since the electrodes donot need to be cut from a web. In addition, the sintered anode 302 andthe sintered cathode 304 can include standalone slugs with the sinteredportion being monolithic without a substrate.

In various examples, the void space 308 can be conical and the sinteredcathode 304 can be conical. In one example, the void space 308 of thesintered anode 312 can be shaped like a fin and the sintered cathode 304can have a fin shape. In one example, the capacitor can include aplurality of sintered cathodes 304 forming a bed-of-nails typestructure. The sintered anode 302 can then be dropped over the bed ofnails structure. Such shapes and structures allow for ease of assemblywith lower complexity.

In one example, the sintered cathode 304 can include a high capacitancecoating on an outer surface 310 of the sintered cathode 304. Forexample, an ALD (atomic layer deposition) coating of titanium can beapplied to a portion of, or all of, the outer surface 306. Otherexamples can include ruthenium, hafnium, etc. The high capacitancecoating will provide a much higher capacitance than just aluminum.

FIG. 4 shows the sintered anode 302 and the sintered cathode 304 andfurther includes a separator 402 between the sintered anode 302 and thesintered cathode 304. In an example, the separator 402 can include ahigh dielectric polymer directly applied to an outer surface of thesintered cathode 304. For example, a high dielectric and hydrophilicpolymer can be electro-spun directly onto the sintered cathode surface.In one example, a microsphere coating applied to the surface of thesintered cathode 304 can be the separator 402. Omitting a conventionalseparate paper separator can aid manufacturing because there are fewerassembly steps. Moreover, the separator 402 allows for complex cathodeshapes to be used that would not be feasible using only paperseparators. In some examples, the separator can be applied to thesintered anode 302.

FIGS. 5-8 shows various shapes and configurations for sintered anodes502 and 504 and sintered cathodes 510, in accordance with someembodiments. In this example, the sintered anodes 502 and 504 aretriangular in shape and have one or more mating portions such as voidspaces comprising a rounded cut-out 512 at one or more corners of thetriangular sintered anode 502, 504. The sintered cathodes 510 caninclude a cylindrical shape similar to the shape of the void spaces ofanodes 502, 504. As discussed above, the sintered cathodes 510 can havean electro-spun (or microsphere) coating on the outer surface of thecylindrical shape to act as the separator.

The sintered anodes 502, 504 can be arranged together in a side by sideconfiguration in various patterns with a plurality of cylindricalcathodes 302 located at the rounded out corners in the void spaces ofeach of the plurality of sintered anodes 502, 504. For example, FIG. 7shows similarly shaped sintered anodes 504 arranged in top/bottomalternating pattern. FIG. 8 shows an alternating pattern, but using thethinner anodes 502 to allow the overall shape to be shaped andstructured as desired. In various embodiments, many other patterns canbe formed using the sintered anodes 502, 504.

FIG. 9 shows sintered anodes 602, 604 and sintered cathodes 610, inaccordance with one embodiment. The sintered anodes 602 and 604 can begenerally rectangular with mating portion such as void spaces, includingcut-outs 606 at one or more corners of the sintered anode 602, 604. Asabove, the sintered cathodes 610 can be cylindrical in shape and caninclude a dielectric coating to act as a separator. The sintered anodes602, 604 can be arranged in various patterns and the sintered cathodes610 fit matingly into the combined void spaces formed by the cut-outs606. Such “Lego™-like” or “puzzle-like” structures allow for thecreation of configurations that do not require the sandwich-likestacking of current capacitors.

FIGS. 10 and 11 show a perspective view of sintered anodes 602, 604 andthe sintered cathodes 610 as inserted into a capacitor case 620.

FIG. 12 shows a perspective view of a sintered anode 655 having acentral hole 652 and a sintered cathode 654 and further sinteredcathodes 610, in accordance with one embodiment. This example is similarto the embodiment of FIGS. 9-11, but further includes a cylindricalsintered cathode 654 inserted into hole 652, with cathodes 610 locatedat the corners of the anodes 655. The anodes 655 and cathodes 654 and610 are inserted into a capacitor case 660.

FIGS. 13 and 14 show front and rear perspective views of a sinteredanode 670 and sintered cathode 680, in accordance with one embodiment.In this example, the sintered cathode includes a plurality of conicalcathode peaks 682, having a bed-of-nails structure. The anode 670includes a plurality of mating portions, such as conical void spaces 684that correspond to the cathode peaks 682. Such shapes and structuresallow for ease of assembly with lower complexity.

FIGS. 15 and 16 show the sintered anode 670 and the sintered cathode 680assembled with a separator 690 located on each of peaks 682 of thecathode 680. As discussed above, the separator 690 can include a highdielectric polymer directly applied to an outer surface of the sinteredcathode 680. For example, a high dielectric and hydrophilic polymer canbe electro-spun directly onto the sintered cathode surface. In oneexample, a microsphere coating applied to the surface of the sinteredcathode 680 can be the separator 690.

FIGS. 17 and 18 show a perspective view of sintered anodes 702 and 703and sintered cathode 704, in accordance with one embodiment. In FIG. 17the anodes 702, 703 and cathode 704 are assembled. FIG. 18 shows anexploded view of anodes 702, 703 and cathode 704. In this example thecathode 704 includes a serpentine fan-like shape with peaks 706 formedon each side of the cathode 704. Each of anodes 702, 703 include matingportions, such as void spaces 710 that are dimensioned to receive thepeaks 706. As previously discussed, a high dielectric and hydrophilicpolymer can be electro-spun directly onto the sintered cathode surfaceor a microsphere coating can be applied as a separator.

In constructing the various capacitors discussed above, an anode can beformed by sintering anode material into a non-rectangular shape having amating portion, such as a void space. A cathode can be formed bysintering cathode material into a shape that mates with the void spaceof the sintered anode such that the sintered cathode matingly fits inthe void space of the sintered anode. As noted, a separator can beapplied to a surface of the cathode (or the anode). The sintered anodeand cathode can then be disposed into a capacitor case, or they can beassembled directly into the capacitor case. In one example, the sinteredcathodes can be formed directly on the capacitor case and then the anodecan be placed over or around the cathodes depending on the configurationdesired.

In any of the examples herein, a high dielectric and hydrophilic polymercan be electro-spun directly onto the sintered cathode surface. In someexamples, a microsphere coating applied to the surface of the sinteredcathode can be the separator. Omitting a conventional separate paperseparator can aid manufacturing because there are fewer assembly steps.In some examples, the separator can be applied to the sintered anode.For some embodiments, a conventional paper separator can be used,depending on the geometry of the sintered anodes and cathodes.

In any of the examples herein, the sintered cathode can include a highcapacitance coating on an outer surface of the sintered cathode. Forexample, an ALD (atomic layer deposition) coating of titanium can beapplied to a portion of, or all of, the outer surface. Other examplescan include ruthenium, hafnium, etc. The high capacitance coating willprovide a much higher capacitance than just aluminum.

This application is intended to cover adaptations or variations of thepresent subject matter. It is to be understood that the abovedescription is intended to be illustrative and not restrictive. Thescope of the present subject matter should be determined with referenceto the appended claims, along with the full scope of legal equivalentsto which such claims are entitled.

What is claimed is:
 1. An apparatus, comprising: a capacitor case sealedto retain electrolyte; a plurality of sintered anodes disposed in thecapacitor case, each sintered anode having a shape wherein the sinteredanode includes a mating portion including a cylindrical hole within eachanode, wherein at least one of the plurality of sintered anodes furtherincludes rounded cut-outs at one or more corners of the sintered anode;a conductor coupled to each of the plurality of sintered anodes, theconductor sealingly extending through the capacitor case to a terminaldisposed on an exterior of the capacitor case; a plurality of sinteredcathodes disposed in the capacitor case, one or more of the plurality ofsintered cathodes having a cylindrical shape that mates with the matingportion of the sintered anode such that the cylindrical sintered cathodematingly fits into the cylindrical hole of the sintered anode; aseparator between adjacent sintered anodes and sintered cathodes; and asecond terminal disposed on the exterior of the capacitor case and inelectrical communication with each of the plurality of the sinteredcathodes, with the terminal and the second terminal electricallyisolated from one another.
 2. The apparatus of claim 1, wherein at leastone of the plurality of sintered anodes has a non-rectangular shape. 3.The apparatus of claim 1, further including a second plurality ofcylindrical cathodes which are further configured to be received by therounded cut-outs of at least one of the plurality of anodes such thatadjacent sintered anodes form a combined rounded void at theirrespective corners to receive the cylindrical sintered cathodes.
 4. Theapparatus of claim 3, wherein at least one of the plurality of sinteredanodes has a rectangular shape with a cut-out at each of the fourcorners of the anode and the cylindrical hole in a body if the anode. 5.The apparatus of claim 4, wherein at least one of the plurality ofsecond cylindrical cathodes are positioned at a common corner of fouradjacent sintered anodes.
 6. The apparatus of claim 1, wherein theseparator includes a high dielectric polymer directly applied to anouter surface of each of the sintered cathode.
 7. The apparatus of claim1, wherein each of the sintered cathodes includes a high capacitancecoating on an outer surface.
 8. The apparatus of claim 1, wherein thesintered anode and the sintered cathode comprise standalone slugs thatincludes the sintered portion, with the sintered portion beingmonolithic.
 9. A system, comprising: a hermetically sealed devicehousing; a battery disposed in the hermetically sealed device housing; acapacitor disposed in the hermetically sealed device housing, thecapacitor comprising: a capacitor case sealed to retain electrolyte; aplurality of sintered anodes disposed in the capacitor case, eachsintered anode having a shape wherein the sintered anode includes amating portion including a cylindrical hole within each anode, whereinat least one of the sintered anodes further includes rounded cut-outs atone or more corners of the sintered anode; a conductor coupled to eachof the plurality of sintered anodes, the conductor sealingly extendingthrough the capacitor case to a terminal disposed on an exterior of thecapacitor case; a plurality of sintered cathodes disposed in thecapacitor case, one or more of the plurality of sintered cathodes havinga cylindrical shape that mates with the mating portion of the sinteredanode such that the cylindrical sintered cathode matingly fits into thecylindrical hole of the sintered anode; a separator between adjacentsintered anodes and sintered cathodes; and a second terminal disposed onthe exterior of the capacitor case and in electrical communication witheach of the plurality of sintered cathodes, with the terminal and thesecond terminal electrically isolated from one another, and anelectronic cardiac rhythm management circuit coupled to the battery andthe capacitor and adapted to discharge the capacitor to provide atherapeutic pulse.
 10. The system of claim 9, wherein at least one ofthe plurality of sintered anodes have a non-rectangular shape.
 11. Thesystem of claim 9, further including a second plurality of cylindricalcathodes which are further configured to be received by the roundedcut-outs of one or more of the plurality of anodes such that adjacentsintered anodes form a combined rounded void at their respective cornersto receive the cylindrical sintered cathodes.
 12. The system of claim11, wherein each sintered anode has a rectangular shape with a cut-outat each of the four corners of the anode and the cylindrical hole in abody if the anode.
 13. The system of claim 12, wherein at least one ofthe second plurality of cylindrical cathodes are positioned at a commoncorner of four adjacent sintered anodes.
 14. A method, comprising:sintering anode material into a shape wherein the sintered anodeincludes a mating portion including a cylindrical hole within eachanode, wherein the sintered anode further includes rounded cut-outs atone or more corners of the sintered anode; sintering cathode materialinto a cylindrical shape that mates with the mating portion of thesintered anode such that the cylindrical sintered cathode matingly fitsinto the cylindrical hole of the sintered anode; disposing a separatorbetween the sintered anode and the sintered cathode; and disposing thesintered anode and sintered cathode into a capacitor case.
 15. Themethod of claim 14, wherein the separator includes a high dielectricpolymer directly applied to an outer surface of the sintered cathode.16. The method of claim 14, further including a second plurality ofcylindrical cathodes which are further configured to be received by therounded cut-outs of the anodes.
 17. The method of claim 16, whereinadjacent sintered anodes form a combined rounded void at theirrespective corners to receive the cylindrical sintered cathodes.